Useless 100 Mbps fiber line

I reported an intermittent disconnection on the 26/3/2021. Line speed and distance coverage was good only problem was it intermittently disconnected. Vox then tried to send new firmware to the router and router stopped working. Waited about 3 days for new router and new router was just installed and password was set up. after the installation of new router i basically had to internet. tested my "100 Mbps" line and it was 35 Mbps on 5 G and only about 5Mbps on 2 G. Router distance also only about 2 - 3 metres. Tried with numerous people from vox over the phone to get this sorted but no luck. They sent a Technician out today and he updated the firmware but still no luck. 5 metres from router i get 13 Mbps on 2G. 5G basically only works when you next to router. In my bedroom where the previous router worked 100 % i dont have internet. I will have 3 out of 4 bars signal strength but line tests at 2 Mbps. Now when you phone vox they say interference. So where did it come from now , the new router? Previous one worked 100%. Best is this is going on now 2nd week struggling with this internet but hey , you have to pay full price. Even with no one thats able to sort out this Vox issue. Now i have to wait AGAIN for feedback. So i pay , sit at home with basically no internet. cant watch tv as we stream. Basically cant use phone unless you at the router. So Vox what am i paying for? And stop even coming with these silly stories about extenders and trying to get more money out of me. Its not going to work. Ive never used and there was never need for extenders because every thing WAS working. If you cant fix the issue take out your router and i will go over to a company that has customer service.